Merge branch 'master' into fix-m-issue

Help on License

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+Provides guidance to Huawei engineers how to add or modify the license announcement
+during the development.
+
+A. In the case that you add a new file, the text below should be added in the head.
+
+    Copyright 2018 Huawei Technologies Co.,Ltd.
+
+    Licensed under the Apache License, Version 2.0 (the "License"); you may not use
+    this file except in compliance with the License.  You may obtain a copy of the
+    License at
+
+      http://www.apache.org/licenses/LICENSE-2.0
+
+    Unless required by applicable law or agreed to in writing, software distributed
+    under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR
+    CONDITIONS OF ANY KIND, either express or implied.  See the License for the
+    specific language governing permissions and limitations under the License.
+
+B. In the case that copyright exists and file is not modified, do not add copyright.
+
+C. In the case that you modify one existing file, the text below should be added after
+the existing license.
+
+    Huawei has modified this source file.
+    Copyright 2018 Huawei Technologies Co., Ltd.